BirdAnalyst
Species · BCR 10 · BBS 2025 Release · 1966–2024

Brown-headed Cowbird In Northern Rockies

All regionsNorthern RockiesGeneralists

Brown-headed Cowbird in Northern Rockies has increased: up 42% on the route-weighted index since 1970.

+42%Since 1970TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
220Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

No notable trend signals for Brown-headed Cowbird in Northern Rockies. See the full index history below.

Brown-headed Cowbird In Northern Rockies Population Forecast

If the recent trend holds, Brown-headed Cowbird in Northern Rockies is projected to rise about 60% by 2029 — from 4.3 in 2024 to a central estimate of 6.9 (95% range 3.5–10). A 5-year backtest shows a typical error of ±73.6%, with 40% of held-out values landing inside the 95% band.

+60%Change by 2029TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
6.9Projected 2029 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
3.5–1095% range95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
±73.6%Backtest errorBacktest errorTypical error when we hold out the most recent years, forecast them, and compare to what actually happened. Lower means a more trustworthy projection.Full methodology →
If the recent trend holds, Brown-headed Cowbird in Northern Rockies is projected to rise about 60% by 2029 — from 4.3 in 2024 to a central estimate of 6.9 (95% range 3.5–10). A 5-year backtest shows a typical error of ±73.6%, with 40% of held-out values landing inside the 95% band.19682029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →95% low95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →95% high95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
20256.83.410
20266.83.510
20276.83.510
20286.83.510
20296.93.510

Routes In Northern Rockies

Routes recording Brown-headed Cowbird in Northern Rockies.
Recent countThe raw number of individuals recorded on this route in its most recent survey year. A single-route tally, not a trend.Full methodology →
CascadeIDAHO551984
AugustaMONTANA362024
WoodruffUTAH272024
St MaryMONTANA252008
MidvaleWYOMING252022
Wolf CreekMONTANA212022
RaynesfordMONTANA212024
SpartaOREGON202001
RandolphUTAH202024
CabartonIDAHO182023
BoulderMONTANA172024
Muddy CreekMONTANA172015
Clyde ParkMONTANA142024
Silver CreekOREGON142024
NewbridgeOREGON142024
PolsonMONTANA132024
Pablo Res.MONTANA132024
Deer ParkWASHINGTON132015
Church HillMONTANA122024
Hebgen LakeMONTANA122024
Rock RiverWYOMING122022
Mount VernonOREGON112024
Hayden ValWYOMING111986
KalispellMONTANA102024
Red RockMONTANA102024

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.